[Geospatial Data] Add initial support to decode layers

This PR adds support to decode layers that only use startYear and endYear decode parameters in the Geospatial Data module.

Testing

On your local Strapi instance, create a new layer called “Tree Cover Loss” of type deckgl

Paste the following config:

{
"@@type": "DecodeLayer",
"source": {
"type": "raster",
"tiles": [
  "https://tiles.globalforestwatch.org/umd_tree_cover_loss/v1.10/tcd_30/{z}/{x}/{y}.png"
],
"maxzoom": 12,
"minzoom": 2
},
"styles": [
{
  "id": "tree-cover-loss",
  "type": "raster",
  "paint": {
    "raster-opacity": {
      "o": "@@#params.opacity",
      "@@function": "setOpacity"
    }
  },
  "layout": {
    "visibility": {
      "v": "@@#params.visibility",
      "type": "deckgl",
      "@@function": "setVisibility"
    }
  }
}
],
"decodeParams": {
"endYear": "@@#params.endYear",
"startYear": "@@#params.startYear"
},
"decodeFunction": "// values for creating power scale, domain (input), and range (output)\nfloat domainMin = 0.;\nfloat domainMax = 255.;\nfloat rangeMin = 0.;\nfloat rangeMax = 255.;\nfloat exponent = zoom < 13. ? 0.3 + (zoom - 3.) / 20. : 1.;\nfloat intensity = color.r * 255.;\n// get the min, max, and current values on the power scale\nfloat minPow = pow(domainMin, exponent - domainMin);\nfloat maxPow = pow(domainMax, exponent);\nfloat currentPow = pow(intensity, exponent);\n// get intensity value mapped to range\nfloat scaleIntensity = ((currentPow - minPow) / (maxPow - minPow) * (rangeMax - rangeMin)) + rangeMin;\n// a value between 0 and 255\ncolor.a *= zoom < 13. ? scaleIntensity / 255. : color.g;\nfloat year = 2000.0 + (color.b * 255.);\n// map to years\nif (year >= startYear && year <= endYear && year >= 2001.) {\n  color.r = 220. / 255.;\n  color.g = (72. - zoom + 102. - 3. * scaleIntensity / zoom) / 255.;\n  color.b = (33. - zoom + 153. - intensity / zoom) / 255.;\n} else {\n  color.a = 0.;\n}"
}

Paste the following params_config:

[
{
"key": "opacity",
"default": 1
},
{
"key": "visibility",
"default": true
},
{
"key": "startYear",
"default": 2001
},
{
"key": "endYear",
"default": 2022
}
]

Paste the following legend_config:

{
"type": "basic",
"items": [
{
  "color": "#dc6c9a",
  "value": "Tree cover loss"
}
]
}

Assign the layer to a layer group (and a page if you're creating a new layer group).
Open the Geospatial Data module and toggle on the layer
Test that you can hide and change the opacity of the layer

Modify this line as follows:

-      settings,
+      settings: {
+        ...settings,
+        startYear: 2019,
+      }

Check that the data corresponds to this view in Global Forest Watch (Tree cover loss 2019 - 2022)

Note that the UI to change the startYear and endYear values will be implemented in a separate task: ORC-345.

Tracking

ORC-344 - FE - Implement support for decode functions

Orcasa-Platform / orcasa

[Geospatial Data] Add initial support to decode layers #105

Testing

Tracking